Just to clarify, there are no cups used with BB90. You just press the bearings into the frame. You need the V2 bearings (which are slightly larger) or Trek has also offered a shim to press the bearings into before pressing them into the frame.

I personally solved it via some Loctite like was mentioned. Apply a little to the OD of the bearing and press it in.

I have a feeling that it was a Trek that we repaired recently because the BB bearing had worked loose and the rider hadn't realised before wearing away some of the carbon housing which we had to repair. Judging by threads I've seen this could be a common issue?

Are you sure it is installed correctly to begin with and spacers on the proper side?

Example, my BB86 in my foil, cranks slipped/bearing came loose. I had put the wavy on the ND side, like my BB30 setup. Well, that is wrong for my S975 Quarq, the wavy goes drive side, no spacers on the left, torque to spec, no problems.

The cranks and torque of the bolt hold the bearings pressed into the frame. At most, they would only creak if they can wiggle slightly while standing on it with some power.

They should never slip/move around the bearing left/right in the frame or cups when spaced, torqued and installed correctly, whatever the instructions say for your cranks/bearing setup. If it does, and everything is correct and it creaks, then loctite 609 will solve that.

But if the bearing diameter is off .1-2 mm, that could cause creaking also, but it wont move side to side still. That is a spacer, torque wavy issue IMHO.

Verify proper install and torque. Then I would take it to the Trek dealer or call them and find out what the deal is.

Something to think about before you Loctite bearings,adaptors or sleeves into a carbon frame is that the standard way for disassembly of most Loctite bearing and stud mounts is applying heat. In the case of Loctite 609 and 641 250º C. See the TDS :

Do you want to heat your carbon frame up to that temp? I wouldn't on mine. Many manufacturers tell you not leave your frame in a closed car on a hot day! Just like your dog, it may die.

I was skeptical when Trek brought out the all carbon BB and am even more so now that I see they have special oversize bearings and shims for out of tolerance bottom bracket moulding.

The TDS also says that Loctite 609/641 is not recommended on thermoplastics. The fact that it may be recommended by various manufacturers leads me to assume that these designs are having service issues. I work in the automotive industry and most of the gap filling/sleeve retaining Loctite type products require heat and or quite a bit of force to take them apart. Pounding or rigging up an elaborate puller on a lightweight bottom bracket with little material to begin with seems like asking for trouble.

However, you may be left with little choice but to use these products so you have a useable crank/bearing assembly. But it may make for a trashed frame when it comes time to replace the bearings.

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